*WORKS* I have set up a VPN server on a Windows 2003 server (std) by following the RRAS wizard, allowing access for a user, and then forwarding port (on the router) 1723 TCP to the server's internal IP. It works just fine. This has one network port and the router is a Linksys. It has both port-forwarding of 1723 to the server and PPTP passthrough enabled.
*WORKS* I did this same thing on another WIndows 2003 server SBS netowork and it works also. This one has one network port and a Microsoft MN-700 router. It has port forwarding enabled for 1723 TCP to the server. (PPTP pass-through is not mentioned in the config screens)
*DOES NOT WORK!* I tried the same thing on a another Windows SBS 2003 server (a third network) and I can not connect. It gets to "Verifying username and password" then says "error 721. the remote computer did not respond". This server also has one network port and has a D-Link DI-614+ router. I tried both TCP 1723 and UDP 500 forwarding to the server.
Thanks for your help.